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Biomedical subjects

B T Poll-The

Publications and source records attributed to B T Poll-The.

At least 37 records · Page 2Linked to original sources
PubMed2000

Molecular characterization of 3-phosphoglycerate dehydrogenase deficiency--a neurometabolic disorder associated with reduced L-serine biosynthesis.

3-phosphoglycerate dehydrogenase (PHGDH) deficiency is a disorder of L-serine biosynthesis that is characterized by congenital microcephaly, psychomotor retardation, and seizures. To investigate the molecular basis for this disorder, the PHGDH mRNA sequence was characterized, and six patients from four families were analyzed for sequence variations. Five patients from three different families were homozygous for a single nucleotide substitution predicted to change valine at position 490 to methionine. The sixth patient was homozygous for a valine to methionine substitution at position 425; both mutations are located in the carboxyterminal part of PHGDH. In vitro expression of these mutant proteins resulted in significant reduction of PHGDH enzyme activities. RNA-blot analysis indicated abundant expression of PHGDH in adult and fetal brain tissue. Taken together with the severe neurological impairment in our patients, the data presented in this paper suggest an important role for PHGDH activity and L-serine biosynthesis in the metabolism, development, and function of the central nervous system.

Amino Acid Metabolism, Inborn Errors↗
PubMed2000

[Identification of the gene for hyper-IgD syndrome: a model of modern genetics].

Hyperimmunoglobulinaemia D and periodic fever syndrome (HIDS) is a rare autosomal recessive disorder. Patients suffer from recurrent attacks (3-6 days) with fever, abdominal distress, lymphadenopathy, skin lesions and arthralgias. Patients display a constantly elevated serum IgD which serves as a biological marker of the disease. Recently, the gene for HIDS was discovered by two independent groups using positional and functional cloning methods. One group used linkage analysis (positional cloning) and was able to locate the gene for HIDS on the long arm of chromosome 12 (12q24). Mevalonate kinase was an interesting candidate gene because patients with a near complete absence of this enzyme (mevalonic aciduria) do exhibit attacks of fever. Indeed subsequent data showed that there was a decreased enzyme activity due to missense mutations in the mevalonate kinase gene. The other group detected slightly elevated urinary excretion of mevalonic acid during attacks in a HIDS patient (functional cloning). The enzyme activity of mevalonate kinase was lower in cultured cells and sequence analysis identified several missense mutations in cDNA encoding for mevalonate kinase. Mevalonate kinase is a key enzyme in the cholesterol synthesis pathway and it is rather surprising that a defect in the cholesterol metabolism can cause a periodic inflammatory disease such as HIDS.

Biomarkers↗
PubMed2000

[Phenylketonuria: a children's disease in adulthood].

The prognosis for patients with phenylketonuria (PKU) has improved greatly with early institution of treatment after birth. It was assumed that the diet could be terminated after adolescence but there are strong indications that hyperphenylalaninaemia can have detrimental effects in adult patients. Hyperphenylalaninaemia can cause reversible white matter abnormalities, and is also associated with psychiatric illness, which improves with lowering of the plasma phenylalanine level. Even optimally treated patients generally have a decreased performance with neuropsychological tests compared with subjects without PKU. Elevation of the plasma phenylalanine level leads to worsening of neuropsychological performance, lowering of the level leads to improved performance. Strict metabolic control is necessary during pregnancy in women with PKU in view of the increasing frequency of congenital abnormalities with increasing phenylalanine level. The complexity and demanding nature of the diet treatment make specialised facilities for optimal medical and paramedical care mandatory.

Adult↗
PubMed2000

Prenatal diagnosis in adenylosuccinate lyase deficiency.

Adenylosuccinate lyase deficiency, an autosomal recessive inborn error of purine synthesis, provokes accumulation in body fluids of succinylaminoimidazolecarboxamide riboside and succinyladenosine, the dephosphorylated derivatives of the two substrates of the enzyme. Most patients display severe psychomotor retardation, often accompanied by epilepsy and/or autistic features, although some are only mildly retarded. About 20 mutations are known. Prenatal diagnosis was performed twice on chorion villi of the mother of a previously diagnosed patient with a C5T mutation (exon 1) on the maternal allele, and a C1185A mutation (exon 11) on the paternal allele. Both suppress a Fnu4HI restriction site. In a first fetus, incubation of PCR products generated from genomic DNA of exon 1 with Fnu4HI yielded a 113 bp fragment from a control and the father's gene, and both a 113 bp and 170 bp fragment from the mother, affected sibling and fetus. Incubation of PCR products of exons 11-12 with Fnu4HI yielded a 550 bp fragment from a control and the mother's gene, and a 550 bp and 600 bp fragment from the father, affected sibling and fetus. Assay of adenylosuccinate lyase on the aborted fetal liver confirmed the enzyme deficiency. A second fetus displayed only the maternal mutation.

Abortion, Induced↗
PubMed2000

Congenital hepatic fibrosis in 3 siblings with phosphomannose isomerase deficiency.

Congenital hepatic fibrosis is a rare disorder of intrahepatic bile ducts with the persistence of embryological bile duct structures in ductal plate configuration. Three siblings aged 18, 17 and 14 years old were found to have congenital hepatic fibrosis associated with a deficiency of the enzyme phosphomannose isomerase. The clinical symptoms were recurrent attacks of persistent vomiting with diarrhea and mild hepatomegaly. The biochemical abnormalities included elevated serum transferases during attacks, clotting factor deficiencies and persistent hypoalbuminemia. In the youngest patient protein-losing enteropathy was present. Liver biopsies of the three patients taken when they were 1, 3 and 14 years old showed an excess of bile duct structures in ductal plate configuration with mild fibrosis in the portal triads. In one patient the liver biopsy was repeated after 18 years and showed only a mild progression of fibrosis in the portal triads. Duodenal biopsies taken in infancy in two of the three patients did not show any abnormalities. Recognition of phosphomannose isomerase deficiency in association with congenital hepatic fibrosis and protein-losing enteropathy is important, because some of the clinical symptoms are potentially treatable by oral mannose therapy.

Adolescent↗
PubMed2000

Hepatic peroxisomes in isolated hyperpipecolic acidaemia: evidence supporting its classification as a single peroxisomal enzyme deficiency.

Hyperpipecolic acidaemia is still regarded as a peroxisomal assembly deficiency. The enzyme responsible for the accumulation of pipecolic acid is located in the peroxisomes in man. We studied the appearance and alterations of peroxisomes in liver biopsy material from three unrelated children suffering from isolated hyperpipecolic acidaemia, in which only the metabolism of pipecolic acid is disturbed, using light and electron microscopy after cytochemical staining for visualisation of peroxisomes. Morphometric results showed the presence of normal-sized to small peroxisomes, an increase in number and abnormally shaped organelles, suggesting enhancement of metabolic efficiency. In one case enlarged organelles were observed. Skin fibroblasts were studied in all patients: their peroxisomes appeared to be normal. The obvious presence of peroxisomes in isolated HPA indicates that this disorder should be classified as a single peroxisomal enzyme deficiency.

Acyl-CoA Oxidase↗
PubMed2000

Isolated and contiguous glycerol kinase gene disorders: a review.

Glycerol kinase deficiency (GKD) is an X-linked recessive disorder. There are two types. an isolated form and a complex form. We review the clinical, biochemical and molecular genetic features of GKD. The clinical and biochemical phenotype of isolated GKD may vary from a life-threatening childhood metabolic crisis to asymptomatic adult 'pseudohypertriglyceridaemia', resulting from hyperglycerolaemia. To date 38 patients from 24 families with isolated GKD have been reported. At least 7 of these patients had a metabolic crisis during a catabolic condition. The complex GKD is an Xp21 contiguous gene syndrome involving the glycerol kinase locus together with the adrenal hypoplasia congenita (AHC) or Duchenne muscular dystrophy (DMD) loci or both. Clinical features of a patient with complex GKD depend on the loci that are involved. Approximately 100 patients from 78 families with a complex GKD have been reported. Seventeen patients with complex GKD (AHC-GKD-DMD or AHC-GKD) died in the neonatal period or early childhood because of unrecognized or inappropriate management of adrenal dysfunction. Since the outcome of the crisis in GKD is highly dependent on the physicians' knowledge of the disease, we devised an algorithmic approach to the diagnosis. From molecular genetic investigations of isolated GKD, 7 missense mutations, 2 splice site mutations, I nonsense mutation, 1 Alu Sx insertion and 2 small deletions were reported for isolated GKD in 13 unrelated families. In 4 families consisting of more than one patient with the same biochemical and genetic defect, the phenotypic variability of the isolated GKD was remarkable. The clinical variability in isolated GKD cannot be explained by biochemical or by molecular heterogeneity. Isolated GKD patients showed a tendency towards hypoglycaemia with hyperketonaemia; whether the clinical symptoms of GKD are caused by dysfunction of gluconeogenesis and/or ketolysis needs to be investigated further.

Adrenal Insufficiency↗
PubMed2000

Mutation detection in the aspartoacylase gene in 17 patients with Canavan disease: four new mutations in the non-Jewish population.

Canavan disease is a severe progressive autosomal recessive disorder, which is characterised by spongy degeneration of the brain. The disease is caused by mutations in the aspartoacylase gene. Two different mutations were reported on 98% of the alleles of Ashkenazi Jewish patients, in which population the disease is highly prevalent. In non-Jewish patients of European origin, one mutation (914C > A) is found in 50% of the alleles, the other alleles representing all kinds of different mutations. We here describe the results of the mutation analysis in 17 European, non-Jewish patients. Ten different mutations were found, of which four had not been described before (H21P, A57T, R168H, P181T). A deletion of exon4, which until now had only been described once, was revealed in all five alleles of Turkish origin tested, indicating that this is a founder effect in the Turkish population.

Amidohydrolases↗
PubMed2000

Phytanoyl-CoA hydroxylase activity is induced by phytanic acid.

Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a branched-chain fatty acid present in various dietary products such as milk, cheese and fish. In patients with Refsum disease, accumulation of phytanic acid occurs due to a deficiency of phytanoyl-CoA hydroxylase, a peroxisomal enzyme containing a peroxisomal targeting signal 2. Recently, phytanoyl-CoA hydroxylase cDNA has been isolated and functional mutations have been identified. As it has been shown that phytanic acid activates the nuclear hormone receptors peroxisome proliferator-activated receptor (PPAR)alpha and all three retinoid X receptors (RXRs), the intracellular concentration of this fatty acid should be tightly regulated. When various cell lines were grown in the presence of phytanic acid, the activity of phytanoyl-CoA hydroxylase increased up to four times, depending on the particular cell type. In one cell line, HepG2, no induction of phytanoyl-CoA hydroxylase activity was observed. After addition of phytanic acid to COS-1 cells, an increase in phytanoyl-CoA hydroxylase activity was observed within 2 h, indicating a quick cell response. No stimulation of phytanoyl-CoA hydroxylase was observed when COS-1 cells were grown in the presence of clofibric acid, 9-cis-retinoic acid or both ligands together. This indicates that the activation of phytanoyl-CoA hydroxylase is not regulated via PPARalpha or RXR. However, stimulation of PPARalpha and all RXRs by clofibric acid and 9-cis-retinoic acid was observed in transient transfection assays. These results suggest that the induction of phytanoyl-CoA hydroxylase by phytanic acid does not proceed via one of the nuclear hormone receptors, RXR or PPARalpha.

Alitretinoin↗
PubMed2000

Hypomyelination and reversible white matter attenuation in 3-phosphoglycerate dehydrogenase deficiency.

White matter abnormalities are a feature of many inborn errors of metabolism and magnetic resonance imaging (MRI) of the brain has become an important tool in the diagnostic work-up of these disorders. Recently, patients were reported with a potentially treatable disorder of serine biosynthesis. They presented with congenital microcephaly, severe psychomotor retardation and intractable seizures. Low concentrations of the amino acids serine, glycine as well as 5-methyltetrahydrofolate were found in plasma and CSF and were due to a deficiency of the enzyme 3-phosphoglycerate dehydrogenase (3-PGDH). We studied four patients aged 10 months to 7 years by MRI before and after treatment with amino acids with a follow-up of 16 months to 6 years. Magnetic resonance spectroscopy (MRS) was performed in two patients at 4 and 16 months of treatment. Pre-treatment MRI demonstrated hypomyelination and profound white matter attenuation in all patients. During treatment, a significant increase in white matter volume was found and a progress of myelination in two patients. The most striking finding on MRS during treatment was an elevated level of white matter choline. Serine biosynthesis defects have to be considered in the differential diagnosis of patients with mental retardation, microcephaly, seizures, and on MRI hypomyelination and white matter attenuation.

Amino Acids↗
PubMed2000

Pristanic acid and phytanic acid: naturally occurring ligands for the nuclear receptor peroxisome proliferator-activated receptor alpha.

Phytanic acid and pristanic acid are branched-chain fatty acids, present at micromolar concentrations in the plasma of healthy individuals. Here we show that both phytanic acid and pristanic acid activate the peroxisome proliferator-activated receptor alpha (PPARalpha) in a concentration-dependent manner. Activation is observed via the ligand-binding domain of PPARalpha as well as via a PPAR response element (PPRE). Via the PPRE significant induction is found with both phytanic acid and pristanic acid at concentrations of 3 and 1 microM, respectively. The trans-activation of PPARdelta and PPARgamma by these two ligands is negligible. Besides PPARalpha, phytanic acid also trans-activates all three retinoic X receptor subtypes in a concentration-dependent manner. In primary human fibroblasts, deficient in phytanic acid alpha-oxidation, trans-activation through PPARalpha by phytanic acid is observed. This clearly demonstrates that phytanic acid itself, and not only its metabolite, pristanic acid, is a true physiological ligand for PPARalpha. Because induction of PPARalpha occurs at ligand concentrations comparable to the levels found for phytanic acid and pristanic acid in human plasma, these fatty acids should be seen as naturally occurring ligands for PPARalpha. These results demonstrate that both pristanic acid and phytanic acid are naturally occurring ligands for PPARalpha, which are present at physiological concentrations.

Animals↗
PubMed1999

Different phenotypic expression in relatives with fabry disease caused by a W226X mutation.

Two male relatives with Fabry disease presented striking differences in clinical symptoms and age of onset. The propositus had retarded statural growth and skeletal dysplasia while his nephew suffered mainly from aggravating acroparesthesia and celiac disease. Fabry disease is an X-linked inborn error of glycosphingolipid metabolism resulting from deficient activity of the lysosomal hydrolase alpha-galactosidase A (alpha-Gal A) enzyme. The alpha-Gal A gene is located at Xq22.1. Efforts to establish genotype-phenotype correlations have been limited because most patients have private mutations. In previous clinical studies performed in families with Fabry disease, marked differences in phenotype are described between affected relatives. This family also demonstrates the difficulty in predicting the clinical phenotype in patients and relatives with the same alpha-Gal A mutation. Furthermore, in the absence of a family history, the diagnosis may be easily missed.

Adolescent↗
PubMed1999

Mutations in MVK, encoding mevalonate kinase, cause hyperimmunoglobulinaemia D and periodic fever syndrome.

Hyperimmunoglobulinaemia D and periodic fever syndrome (HIDS; MIM 260920) is an autosomal recessive disorder characterized by recurrent episodes of fever associated with lymphadenopathy, arthralgia, gastrointestinal dismay and skin rash. Diagnostic hallmark of HIDS is a constitutively elevated level of serum immunoglobulin D (IgD), although patients have been reported with normal IgD levels. To determine the underlying defect in HIDS, we analysed urine of several patients and discovered increased concentrations of mevalonic acid during severe episodes of fever, but not between crises. Subsequent analysis of cells from four unrelated HIDS patients revealed reduced activities of mevalonate kinase (MK; encoded by the gene MVK), a key enzyme of isoprenoid biosynthesis. Sequence analysis of MVK cDNA from the patients identified three different mutations, one of which was common to all patients. Expression of the mutant cDNAs in Escherichia coli showed that all three mutations affect the activity of the encoded proteins. Moreover, immunoblot analysis demonstrated a deficiency of MK protein in patient fibroblasts, indicating a protein-destabilizing effect of the mutations.

Amino Acid Substitution↗